The great Carl Sagan famously popularized the saying:

Extraordinary claims require extraordinary evidence.

I’ve always disliked that saying. It was intended as a shout-out to objectivity, rationalism, and healthy skepticism, but it has the opposite effect for me. Any writer will tell you that overuse of adjectives will actually weaken the point the writer is trying to make. The same is happening here.

The difference between “claims” and “extraordinary” claims is subjective. The same goes for evidence. Any two people could argue about whether something reaches the threshold of “extraordinary” or not, and there’s usually not much evidence to bring to bear on either side. The solid foundation of the objective is weakened by cracks of the subjective.

I have to admit, though, it’s catchier (or should I say very, very considerably much more catchier?) than:

Claims require evidence.

Wording it in terms of proportion instead of absolutes seems a good way forward, as attributed to David Hume:

A wise man, therefore, proportions his belief to the evidence.

That sounds wise to me. It’s also a useful working definition of “faith”, that that’s for another posting some other time.